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  • Table index design

    - by Swoosh
    I would like to add index(s) to my table. I am looking for general ideas how to add more indexes to a table. Other than the PK clustered. I would like to know what to look for when I am doing this. So, my example: This table (let's call it TASK table) is going to be the biggest table of the whole application. Expecting millions records. IMPORTANT: massive bulk-insert is adding data in this table table has 27 columns: (so far, and counting :D ) int x 9 columns = id-s varchar x 10 columns bit x 2 columns datetime x 5 columns INT COLUMNS all of these are INT ID-s but from tables that are usually smaller than Task table (10-50 records max), example: Status table (with values like "open", "closed") or Priority table (with values like "important", "not so important", "normal") there is also a column like "parent-ID" (self - ID) join: all the "small" tables have PK, the usual way ... clustered STRING COLUMNS there is a (Company) column (string!) that is something like "5 characters long all the time" and every user will be restricted using this one. If in Task there are 15 different "Companies" the logged in user would only see one. So there's always a filter on this one. Might be a good idea to add an index to this column? DATE COLUMNS I think they don't index these ... right? Or can / should be?

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  • g-wan - reproducing the performance claims

    - by user2603628
    Using gwan_linux64-bit.tar.bz2 under Ubuntu 12.04 LTS unpacking and running gwan then pointing wrk at it (using a null file null.html) wrk --timeout 10 -t 2 -c 100 -d20s http://127.0.0.1:8080/null.html Running 20s test @ http://127.0.0.1:8080/null.html 2 threads and 100 connections Thread Stats Avg Stdev Max +/- Stdev Latency 11.65s 5.10s 13.89s 83.91% Req/Sec 3.33k 3.65k 12.33k 75.19% 125067 requests in 20.01s, 32.08MB read Socket errors: connect 0, read 37, write 0, timeout 49 Requests/sec: 6251.46 Transfer/sec: 1.60MB .. very poor performance, in fact there seems to be some kind of huge latency issue. During the test gwan is 200% busy and wrk is 67% busy. Pointing at nginx, wrk is 200% busy and nginx is 45% busy: wrk --timeout 10 -t 2 -c 100 -d20s http://127.0.0.1/null.html Thread Stats Avg Stdev Max +/- Stdev Latency 371.81us 134.05us 24.04ms 91.26% Req/Sec 72.75k 7.38k 109.22k 68.21% 2740883 requests in 20.00s, 540.95MB read Requests/sec: 137046.70 Transfer/sec: 27.05MB Pointing weighttpd at nginx gives even faster results: /usr/local/bin/weighttp -k -n 2000000 -c 500 -t 3 http://127.0.0.1/null.html weighttp - a lightweight and simple webserver benchmarking tool starting benchmark... spawning thread #1: 167 concurrent requests, 666667 total requests spawning thread #2: 167 concurrent requests, 666667 total requests spawning thread #3: 166 concurrent requests, 666666 total requests progress: 9% done progress: 19% done progress: 29% done progress: 39% done progress: 49% done progress: 59% done progress: 69% done progress: 79% done progress: 89% done progress: 99% done finished in 7 sec, 13 millisec and 293 microsec, 285172 req/s, 57633 kbyte/s requests: 2000000 total, 2000000 started, 2000000 done, 2000000 succeeded, 0 failed, 0 errored status codes: 2000000 2xx, 0 3xx, 0 4xx, 0 5xx traffic: 413901205 bytes total, 413901205 bytes http, 0 bytes data The server is a virtual 8 core dedicated server (bare metal), under KVM Where do I start looking to identify the problem gwan is having on this platform ? I have tested lighttpd, nginx and node.js on this same OS, and the results are all as one would expect. The server has been tuned in the usual way with expanded ephemeral ports, increased ulimits, adjusted time wait recycling etc.

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  • Good ways to earn income as a self employed developer

    - by nullptr
    I was just wondering if people could share their experiences and ideas about generating / earning income from a software product or service they have personally developed. To me this seems like a good way to earn a living while doing what we love (programming) and working on projects and problems which interest us. Ie, NOT boring bank or marketing software etc 9-5 all week... Some ideas I have are things like web 2.0 style sites (Facebook,Youtube,Twitter,Digg) etc etc... - These can be very very profitable as we all know but can take years to take off. Are there ways to survive until/if this does happen? Mobile applications. Iphone, Google Android and the new up coming Nintendo DS app store. These have good potential to make it easy to find a market for your application and make selling it easy. Shareware/PC software. A bit 80's and 90's and you kind of need to be a salesman/marketer to sell it but its the only other thing I can think of. Also im not talking about doing freelance work. Im only interested in idea's you can come up with and develop your self (not other peoples ideas or problems which are you are payed to develop). Things that a sole developer or at the most 2 developers could work on and have good potential for high returns on investment (in terms of time) would be great. PS, I wish I thought of stackoverflow!

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  • Refining Search Results [PHP/MySQL]

    - by Dae
    I'm creating a set of search panes that allow users to tweak their results set after submitting a query. We pull commonly occurring values in certain fields from the results and display them in order of their popularity - you've all seen this sort of thing on eBay. So, if a lot of rows in our results were created in 2009, we'll be able to click "2009" and see only rows created in that year. What in your opinion is the most efficient way of applying these filters? My working solution was to discard entries from the results that didn't match the extra arguments, like: while($row = mysql_fetch_assoc($query)) { foreach($_GET as $key => $val) { if($val !== $row[$key]) { continue 2; } } // Output... } This method should hopefully only query the database once in effect, as adding filters doesn't change the query - MySQL can cache and reuse one data set. On the downside it makes pagination a bit of a headache. The obvious alternative would be to build any additional criteria into the initial query, something like: $sql = "SELECT * FROM tbl MATCH (title, description) AGAINST ('$search_term')"; foreach($_GET as $key => $var) { $sql .= " AND ".$key." = ".$var; } Are there good reasons to do this instead? Or are there better options altogether? Maybe a temporary table? Any thoughts much appreciated!

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  • Static Logger in seperate thread?

    - by SirLenz0rlot
    Hi all, I've made my Logger, that logs a string, a static class with a static so I can call it from my entire project without having to make an instance of it. quite nice, but I want to make it run in a seperate thread, since accessing the file costs time is that possible somehow and what's the best way to do it? Its a bit of a short discription, but I hope the idea is clear. if not, please let me know. Thanks in advance! btw: any other improvements on my code are welcome as well, i have the feeling not everthing is as efficient as it can be: internal static class MainLogger { internal static void LogStringToFile(string logText) { DateTime timestamp = DateTime.Now; string str = timestamp.ToString("dd-MM-yy HH:mm:ss ", CultureInfo.InvariantCulture) + "\t" + logText + "\n"; const string filename = Constants.LOG_FILENAME; FileInfo fileInfo = new FileInfo(filename); if (fileInfo.Exists) { if (fileInfo.Length > Constants.LOG_FILESIZE) { File.Create(filename).Dispose(); } } else { File.Create(filename).Dispose(); } int i = 0; while(true) { try { using (StreamWriter writer = File.AppendText(filename)) { writer.WriteLine(str); } break; } catch (IOException) { Thread.Sleep(10); i++; if (i >= 8) { throw new IOException("Log file \"" + Constants.LOG_FILENAME + "\" not accessible after 5 tries"); } } } } } enter code here

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  • Convert a image to a monochrome byte array

    - by Scott Chamberlain
    I am writing a library to interface C# with the EPL2 printer language. One feature I would like to try to implement is printing images, the specification doc says p1 = Width of graphic Width of graphic in bytes. Eight (8) dots = one (1) byte of data. p2 = Length of graphic Length of graphic in dots (or print lines) Data = Raw binary data without graphic file formatting. Data must be in bytes. Multiply the width in bytes (p1) by the number of print lines (p2) for the total amount of graphic data. The printer automatically calculates the exact size of the data block based upon this formula. I plan on my source image being a 1 bit per pixel bmp file, already scaled to size. I just don't know how to get it from that format in to a byte[] for me to send off to the printer. I tried ImageConverter.ConvertTo(Object, Type) it succeeds but the array it outputs is not the correct size and the documentation is very lacking on how the output is formatted. My current test code. Bitmap i = (Bitmap)Bitmap.FromFile("test.bmp"); ImageConverter ic = new ImageConverter(); byte[] b = (byte[])ic.ConvertTo(i, typeof(byte[])); Any help is greatly appreciated even if it is in a totally different direction.

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  • svg mouseup event not fired in IE9, unless the debugger is open

    - by Roberto Lupi
    I am using d3 to build a simple chart that the user can edit interactively with the mouse. It works on in all modern common browser (Chrome, Firefox, Safari), except for Internet Explorer 9 where I can start to drag an item but I never get the mouseup event. The strangest bit is that, if I open the debugger, the page works percetly on Internet Explorer 9 as well. My code looks like this: item.append("svg:circle") .attr("class", "handle") .attr("opacity",0.5) .attr("stroke","gray") .attr("cx", bx(0.5)-bx(0)) .attr("r", 10) .style("cursor", "crosshair") .style("pointer-events", "all") .call(d3.behavior.drag() .on("dragstart", function() { dragTarget = d3.select(this); }) .on("drag", function() { this.parentNode.appendChild(this); // put us on the front, not really needed var dragTarget = d3.select(this); dragTarget .attr("cy", function() { return d3.event.dy + parseInt(dragTarget.attr("cy"))}); }) .on("dragend", function(d, i) { newY = parseInt(d3.select(this).attr("cy")); newValue = y.invert(newY); var serieNo = this.__data__.serieNo; console.log([serieNo+1,i+1]); data[serieNo+1][i+1] = newValue; updateBarChart(); onchange(); }) );

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  • php, image dosn't show

    - by lolalola
    Hi, whats wrong with my code. image dosn't show in test2.php file File: test2.php: <img src = "test.php" /> File: test.php session_start(); $md5_hash = md5(rand(0,999)); $security_code = substr($md5_hash, 15, 5); $_SESSION["security_code"] = $security_code; $width = 100; $height = 20; header("Content-type: image/png"); $image = ImageCreate($width, $height); $white = ImageColorAllocate($image, 255, 255, 255); $black = ImageColorAllocate($image, 0, 0, 0); $grey = ImageColorAllocate($image, 204, 204, 204); ImageFill($image, 0, 0, $black); //Add randomly generated string in white to the image ImageString($image, 3, 30, 3, $security_code, $white); //Throw in some lines to make it a little bit harder for any bots to break imageRectangle($image,0,0,$width-1,$height-1,$grey); imageline($image, 0, $height/2, $width, $height/2, $grey); imageline($image, $width/2, 0, $width/2, $height, $grey); imagepng($image); imagedestroy($image);

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  • Why is search functionality not working on this page?

    - by DaveDev
    we deliver micro-site content for our client. Our content is injected into a wrapper that is supplied by another developer. To deliver our content we host the wrapper as well as the content. The user can access this at http://fundcentre.newireland.ie/ (try a search for 'bloxham') For the other content that is not ours, the other developer hosts a similar (though slightly different) wrapper and delivers the content. the user accesses this here: http://www.newireland.ie/ (try a search for 'bloxham') The wrapper contains a search box, which does not work for us but it works for the other developer. I took a look at the network traffic with FireBug but it appears that when I do the search from the wrapper that we're hosting, I'm getting a "407 Proxy Access Denied" error. My guess is their proxy has a problem with the fact that the search is being conducted from a page hosted outside the scope of their proxy. It was also suggested that there were javascript errors on the page that were preventing the search from executing but I can't see any. Also, I don't think I'd get as far as the proxy error if that was the case. I don't really understand this stuff too well though, so could somebody with a bit more experience please take a look and maybe shed some light on this for me? Thanks.

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  • Django url rewrites and passing a parameter from Javascript

    - by William T Wild
    As a bit of a followup question to my previous , I need to pass a parameter to a view. This parameter is not known until the JS executes. In my URLConf: url(r'^person/device/program/oneday/(?P<meter_id>\d+)/(?P<day_of_the_week>\w+)/$', therm_control.Get_One_Day_Of_Current_Thermostat_Schedule.as_view(), name="one-day-url"), I can pass it this URL and it works great! ( thanks to you guys). http://127.0.0.1:8000/personview/person/device/program/oneday/149778/Monday/ In My template I have this: var one_day_url = "{% url personview:one-day-url meter_id=meter_id day_of_the_week='Monday' %}"; In my javascript: $.ajax({ type: 'GET', url: one_day_url , dataType: "json", timeout: 30000, beforeSend: beforeSendCallback, success: successCallback, error: errorCallback, complete: completeCallback }); When this triggers it works fine except I dont necessarily want Monday all the time. If I change the javascript to this: var one_day_url = "{% url personview:one-day-url meter_id=meter_id %}"; and then $.ajax({ type: 'GET', url: one_day_url + '/Monday/', dataType: "json", timeout: 30000, beforeSend: beforeSendCallback, success: successCallback, error: errorCallback, complete: completeCallback }); I get the Caught NoReverseMatch while rendering error. I assume because the URLconf still wants to rewrite to include the ?P\w+) . I seems like if I change the URL conf that breaks the abailty to find the view , and if I do what I do above it gives me the NoREverseMatch error. Any guidance would be appreciated.

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  • Git is not using the first editor in my $PATH

    - by GuillaumeA
    I am using OS X 10.8, and I used brew to install a more recent version of emacs than the one shipped with OS X. The newer emacs binary is installed in /usr/local/bin (24.2.1), and the old "shipped-with-osx" one in /usr/bin (22.1.1). I updated my $PATH env variable by prepending /usr/local/bin to it. It works fine in my shell (ie. typing emacs runs the 24.2.1 version), but when git opens the editor, the emacs version is 22.1.1. Isn't git supposed to use $PATH to find the editor I want to use ? Additional informations: $ type -a emacs emacs is /usr/local/bin/emacs emacs is /usr/bin/emacs emacs is /usr/local/bin/emacs $ env PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin SHELL=/bin/zsh PAGER=most EDITOR=emacs -nw _=/usr/bin/env Please note that I'd prefer not to set the absolute path of my editor directly in my git conf, as I use this conf across multiple systems. EDIT: Here's an bit of my .zshrc: # Mac OS X if [ `uname` = "Darwin" ]; then # Brew binaries PATH="/usr/local/bin":"/usr/local/sbin":$PATH else # Everyone else (Linux) # snip fi So, yes, I could add a line export EDITOR='/usr/local/bin emacs -nw' in the first if, but I'd like to understand why git is not using my PATH variable :)

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  • How to combine apache requests?

    - by Bruce
    To give you the situation in abstract: I have an ajax client that often needs to retrieve 3-10 static documents from the server. Those 3-10 documents are selected by the client out of about 100 documents in total. I have no way of knowing in advance which 3-10 documents the client will require. Additionally, those 100 documents are generated from database content, and so change over time. It seems messy to me to have to make 10 ajax requests for 10 separate documents. My first thought was to write a jsp that could use the include action. ie in pseudo code for (param in params){ jsp:include page="[param]" } But it turns out the tomcat doesn't just include the html resource, it recompiles it, generating a class file every time, which also seems wasteful. Does any one know of a neat solution for combining apache requests to static files to make one request, rather than several, but without the overhead of, for example, tomcat generating extra class files for each static file and regenerating them each time the static file changes? Thanks! Hopefully my question is clear - it's a bit long-winded.

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  • Unexpected results when looking at ASCII codes in C++.

    - by Columbo
    Hello, The bit of code below is extracting ASCII codes from characters. When I convert characters in the normal ASCII region I get the value I expect. When I convert £ and € from the extened region I get a load of 1's padding the INT that I'm storing the character in. e.g. the output of the below is: 45 (ascii E as expected) FFFFFF80 (extended ascii € as expected but padded with ones) It's not causing me an issue but I'm just wondering why this happens. Here's the code... unsigned int asciichar[3]; string cTextToEncode = "E€"; for (unsigned int i = 0; i < cTextToEncode.length(); i++) { asciichar[i] = (unsigned int)cTextToEncode[i]; cout << hex << asciichar[i] << "\n"; } Can anyone explain why this is? Thanks

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  • filling colors on a map - PHP

    - by jeremy
    I am trying to determine how to fill colors onto a map - such as the "Risk" board game map. I've done this before with HTML tables, by pulling an HTML color code from a SQL table and then just using it to fill the cell the color I want it. But for a non-square map, I'm not sure where to look. I have created a very simple two color map - its white with black borders. My desired result is having the 'regions' on the map shaded with a color, based on data in a sql table (just like the "fill" button in Paint). This looks like what I need: http://php.net/manual/en/function.imagefilltoborder.php and now.. how to define the borders... At the moment I have tried nothing, because the question was: how do I have PHP fill parts of an image? I have tried making an image in Paint, and then scratching my head wondering how to fill parts of it. Having stumbled upon a link, let me focus this a bit more: It appears that with imagefilltoborder that I can put an image on my server, perhaps one that looks like a black and white version of the RISK map - black borders and white everything else. Some questions: Is it correct that the 'border' variable should use the color of my border (whatever value black is) so that the code can "see" where the border is? Is it correct that I'll just need to figure out X,Y coords to begin the fill? Does this work if I have 10 different spots to fill on the map? Can I use varying colors from code or pulled from SQL to assign different colors to those 10 spots, and use 10 different X,Y coords to get them all?

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  • What's so bad about building XML with string concatenation?

    - by wsanville
    In the thread What’s your favorite “programmer ignorance” pet peeve?, the following answer appears, with a large amount of upvotes: Programmers who build XML using string concatenation. My question is, why is building XML via string concatenation (such as a StringBuilder in C#) bad? I've done this several times in the past, as it's sometimes the quickest way for me to get from point A to point B when to comes to the data structures/objects I'm working with. So far, I have come up with a few reasons why this isn't the greatest approach, but is there something I'm overlooking? Why should this be avoided? Probably the biggest reason I can think of is you need to escape your strings manually, and most programmers will forget this. It will work great for them when they test it, but then "randomly" their apps will fail when someone throws an & symbol in their input somewhere. Ok, I'll buy this, but it's really easy to prevent the problem (SecurityElement.Escape to name one). When I do this, I usually omit the XML declaration (i.e. <?xml version="1.0"?>). Is this harmful? Performance penalties? If you stick with proper string concatenation (i.e. StringBuilder), is this anything to be concerned about? Presumably, a class like XmlWriter will also need to do a bit of string manipulation... There are more elegant ways of generating XML, such as using XmlSerializer to automatically serialize/deserialize your classes. Ok sure, I agree. C# has a ton of useful classes for this, but sometimes I don't want to make a class for something really quick, like writing out a log file or something. Is this just me being lazy? If I am doing something "real" this is my preferred approach for dealing w/ XML.

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  • Bad idea to have the same object, have a different side effect after method call.

    - by Nathan W
    Hi all, I'm having a bit of a gesign issue(again). Say I have this Buttonpad object: now this object is a wrapper object over one in a com object. At the moment it has a method on it called CreateInto(IComObject). Now to make a new button pad in the Com Object. You do: ButtonPad pad = new ButtonPad(); pad.Title = "Hello"; // Set some more properties. pad.CreateInto(Cominstance); The createinfo method will excute the right commands to buid the button pad in the com object. After it has been created it any calls against it are foward to the underlying object for change so: pad.Title = "New title"; will call the com object to set the title and also set the internal title variable. Basically any calls before the CreateInfo method only affect the .NET object anything after has the side effect of calling the com object also. I'm not very good at sequence diagrams but here is my attempt to explain whats going on: This doesn't feel good to me, it feels like I'm lying to the user about what the button pad does. I was going to have a object called WrappedButtonPad, which is returned from CreateInto and the user could make calls against that to make changes to the Com Object, but I feel having two objects that almost do the same thing but only differ by names might be even worse. Are these valid designs, or am I right to be worried? How else would you handle a object the can create and query a com object?

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  • PHP Recursive Function

    - by Tempname
    In my database I have a hierarchical flat table that returns data ordered by ParentID, ObjectID asc I am having a bit of an issue getting this recursive function to work properly. I get the first ParentChildChild but after that I get nothing else. Any help with this is greatly appreciated. Here is my testing code: $objectArr = array(); $objectData = DAOFactory::getTemplateObjectsDAO()->queryByTemplateID(1); for($i = 0; $i < count($objectData); $i++) { if(empty($objectData[$i]->parentID)) { echo $objectData[$i]->objectID; $objectArr[$i] = $objectData[$i]; $objectArr[$i]->children = array(); $objectArr[$i]->children = getChildren($objectData[$i]->objectID, $objectData); } } function getChildren($objectID, $data) { $childArr = array(); foreach($data as $object) { if($object->parentID == $objectID) { $childArr = $object; $childArr->children = array(); $childArr->children = getChildren($object->objectID, $data); } } return $childArr; } new dBug($objectData); This is the output that I am getting: Fullsize Link

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  • Issues regarding playing audio files in a JME midlet.

    - by Northernen
    I am making a midlet which is to be used to play out local audio files. It is obviously not working. I am getting a null reference on the "is" variable, in the code snippet shown below. 1. try{ 2. System.out.println("path: " + this.getClass()); 3. InputStream is = this.getClass().getResourceAsStream("res/01Track.wav"); 4. p1=Manager.createPlayer(is, "audio"); 5. p1.realize(); 6. p1.prefetch(); 7. p1.start(); 8. } 9. catch(Exception e){ 10. System.out.println(e.getMessage()); 11. } I assume there is something wrong with the "this.getClass().getResourceAsStream("res/01Track.wav")" bit, but I can not for the life of me figure out why, and I have tried referring to the file in 20 different ways. If I printline "this.getClass()" it gives me "path: class Mp3spiller". The absolute path to "01Track.wav" is "E:\Mine dokumenter\Dokumenter\workspace_mobiljava\Mp3spiller\res\01Track.wav". Am I completely wrong in thinking that I should refer relatively to "E:\Mine dokumenter\Dokumenter\workspace_mobiljava\Mp3spiller"? If anyone could point out what I am doing wrong, I would be grateful. I have basically stolen the code from a tutorial I found online, so I would have thought it would be working.

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  • Deleting elements from stl set while iterating through it does not invalidate the iterators.

    - by pedromanoel
    I need to go through a set and remove elements that meet a predefined criteria. This is the test code I wrote: #include <set> #include <algorithm> void printElement(int value) { std::cout << value << " "; } int main() { int initNum[] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }; std::set<int> numbers(initNum, initNum + 10); // print '0 1 2 3 4 5 6 7 8 9' std::for_each(numbers.begin(), numbers.end(), printElement); std::set<int>::iterator it = numbers.begin(); // iterate through the set and erase all even numbers for (; it != numbers.end(); ++it) { int n = *it; if (n % 2 == 0) { // wouldn't invalidate the iterator? numbers.erase(it); } } // print '1 3 5 7 9' std::for_each(numbers.begin(), numbers.end(), printElement); return 0; } At first, I thought that erasing an element from the set while iterating through it would invalidate the iterator, and the increment at the for loop would have undefined behavior. Even though, I executed this test code and all went well, and I can't explain why. My question: Is this the defined behavior for std sets or is this implementation specific? I am using gcc 4.3.3 on ubuntu 10.04 (32-bit version), by the way. Thanks!

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  • (Rails) Creating multi-dimensional hashes/arrays from a data set...?

    - by humble_coder
    Hi All, I'm having a bit of an issue wrapping my head around something. I'm currently using a hacked version of Gruff in order to accommodate "Scatter Plots". That said, the data is entered in the form of: g.data("Person1",[12,32,34,55,23],[323,43,23,43,22]) ...where the first item is the ENTITY, the second item is X-COORDs, and the third item is Y-COORDs. I currently have a recordset of items from a table with the columns: POINT, VALUE, TIMESTAMP. Due to the "complex" calculations involved I must grab everything using a single query or risk way too much DB activity. That said, I have a list of items for which I need to dynamically collect all data from the recordset into a hash (or array of arrays) for the creation of the data items. I was thinking something like the following: @h={} e = Events.find_by_sql(my_query) e.each do |event| @h["#{event.Point}"][x] = event.timestamp @h["#{event.Point}"][y] = event.value end Obviously that's not the correct syntax, but that's where my brain is going. Could someone clean this up for me or suggest a more appropriate mechanism by which to accomplish this? Basically the main goal is to keep data for each pointname grouped (but remember the recordset has them all). Much appreciated. EDIT 1 g = Gruff::Scatter.new("600x350") g.title = self.name e = Event.find_by_sql(@sql) h ={} e.each do |event| h[event.Point.to_s] ||= {} h[event.Point.to_s].merge!({event.Timestamp.to_i,event.Value}) end h.each do |p| logger.info p[1].values.inspect g.data(p[0],p[1].keys,p[1].values) end g.write(@chart_file)

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  • C++ struct, public data members and inheritance

    - by Marius
    Is it ok to have public data members in a C++ class/struct in certain particular situations? How would that go along with inheritance? I've read opinions on the matter, some stated already here http://stackoverflow.com/questions/952907/practices-on-when-to-implement-accessors-on-private-member-variables-rather-than http://stackoverflow.com/questions/670958/accessors-vs-public-members or in books/articles (Stroustrup, Meyers) but I'm still a little bit in the shade. I have some configuration blocks that I read from a file (integers, bools, floats) and I need to place them into a structure for later use. I don't want to expose these externally just use them inside another class (I actually do want to pass these config parameters to another class but don't want to expose them through a public API). The fact is that I have many such config parameters (15 or so) and writing getters and setters seems an unnecessary overhead. Also I have more than one configuration block and these are sharing some of the parameters. Making a struct with all the data members public and then subclassing does not feel right. What's the best way to tackle that situation? Does making a big struct to cover all parameters provide an acceptable compromise (I would have to leave some of these set to their default values for blocks that do not use them)?

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  • `enable_shared_from_this` has a non-virtual destructor

    - by Shtééf
    I have a pet project with which I experiment with new features of the upcoming C++0x standard. While I have experience with C, I'm fairly new to C++. To train myself into best practices, (besides reading a lot), I have enabled some strict compiler parameters (using GCC 4.4.1): -std=c++0x -Werror -Wall -Winline -Weffc++ -pedantic-errors This has worked fine for me. Until now, I have been able to resolve all obstacles. However, I have a need for enable_shared_from_this, and this is causing me problems. I get the following warning (error, in my case) when compiling my code (probably triggered by -Weffc++): base class ‘class std::enable_shared_from_this<Package>’ has a non-virtual destructor So basically, I'm a bit bugged by this implementation of enable_shared_from_this, because: A destructor of a class that is intended for subclassing should always be virtual, IMHO. The destructor is empty, why have it at all? I can't imagine anyone would want to delete their instance by reference to enable_shared_from_this. But I'm looking for ways to deal with this, so my question is really, is there a proper way to deal with this? And: am I correct in thinking that this destructor is bogus, or is there a real purpose to it?

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  • How can I manage building library projects that produce both a static lib and a dll?

    - by Scott Langham
    I've got a large visual studio solution with ~50 projects. There are configurations for StaticDebug, StaticRelease, Debug and Release. Some libraries are needed in both dll and static lib form. To get them, we rebuild the solution with a different configuration. The Configuration Manager window is used to setup which projects need to build in which flavours, static lib, dynamic dll or both. This can by quite tricky to manage and it's a bit annoying to have to build the solution multiple times and select the configurations in the right order. Static versions need building before non-static versions. I'm wondering, instead of this current scheme, might it be simpler to manage if, for the projects I needed to produce both a static lib and dynamc dll, I created two projects. Eg: CoreLib CoreDll I could either make both of these projects reference all the same files and build them twice, or I'm wondering, would it be possible to build CoreLib and then get CoreDll to link it to generate the dll? I guess my question is, do you have any advice on how to structure your projects in this kind of situation? Thanks.

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  • iOS UIImageView dataWithContentsOfURL returning empty

    - by user761389
    I'm trying to display an image from a URL in a UIImageView and I'm seeing some very peculiar results. The bit of code that I'm testing with is below imageURL = @"http://images.shopow.co.uk/image/user_dyn/1073/32/32"; imageURL = @"http://images.shopow.co.uk/assets/profile_images/default/32_32/avatar-male-01.jpg"; NSURL *imageURLRes = [NSURL URLWithString:imageURL]; NSData *imageData = [NSData dataWithContentsOfURL:imageURLRes]; UIImage *image = [UIImage imageWithData:imageData]; NSLog(@"Image Data: %@", imageData); In it's current form I can see data in the output window which is what I'd expect. However if comment out the second imageURL so I'm referencing the first I'm getting empty data and therefore nil is being returned by imageWithData. What is possibly more confusing is that the first image is basically the same as the second but it's been through a PHP processing script. I'm nearly certain that it isn't the script that's causing the issue because if I use this instead imageURL = @"http://images.shopow.co.uk/image/product_dynimg/389620/32/32" the image is displayed and this uses the same image processing script. I'm struggling to find any difference in the images that would cause this to occur. Any help would be appreciated.

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  • T-SQL: how to sort table rows based on 2 columns

    - by Criss Nautilus
    I'm quite stuck with this problem for sometime now.. How do I sort column A depending on the contents of Column B? I have this sample: ID count columnA ColumnB 12 1 A B 13 2 C D 14 3 B C I want to sort it like this: ID count ColumnA ColumnB 12 1 A B 14 3 B C 13 2 C D so I need to sort the rows if the previous row of ColumnB = the next row of ColumnA I'm thinking a loop? but can't quite imagine how it will work... I was thinking it will go like this (maybe) SELECT a.ID, a.ColumnA, a.ColumnB FROM TableA WITH a (NOLOCK) LEFT JOIN TableA b WITH (NOLOCK) ON a.ID = b.ID and a.counts = b.counts Where a.columnB = b.ColumnA the above code isn't working though and I was thinking more on the lines of... DECLARE @counts int = 1 DECLARE @done int = 0 --WHILE @done = 0 BEGIN SELECT a.ID, a.ColumnA, a.ColumnB FROM TableA WITH a (NOLOCK) LEFT JOIN TableA b WITH (NOLOCK) ON a.ID = b.ID and a.counts = @counts Where a.columnB = b.ColumnA set @count = @count +1 END If this was a C code, would be easier for me but t-sql's syntax is making it a bit harder for a noobie like me.

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